Recent activity

The geomagnetic field was quiet to minor storm on December 19. Solar wind
speed ranged between 337 and 558 km/sec under the influence of a coronal stream. This coronal stream is not nearly as strong as it
was during the previous two solar rotations.

At midnight there were 9 spotted regions on the visible disk. A total of 17 C and 1 M class flares
were recorded during the day.

Region 10218 decayed and was spotless by noon.
Region 10220 rotated out of view at the southwest limb.
Region 10223 remained mostly unchanged and quiet. Flare: C2.1 at 06:52 UTC.
Region 10224 decayed quickly in the leading spot section while slow development was observed in the trailing section.
Region 10225 decayed further and lost all trailing spots.
Region 10226 decayed slowly and has a weak magnetic delta structure in a centrally located penumbra. M class flares are
possible. Flares: C2.7 at 00:35, C1.6 at 01:51, C1.7 at 03:08, C2.5 at 05:25, C2.9 at 07:32,
C2.3 at 08:21, C2.3 at
09:42, C2.2 at 13:10 and C2.3 at 20:08 UTC.
Region 10227 could soon become spotless if the current rate of decay persists.
Region 10228 reemerged with a few spots. Flare: C1.4 at 11:18 UTC.
Region 10229 decayed slowly and the large trailing penumbra split into two penumbrae. Another M class flare is possible. Flare: M2.7/2N
long duration event peaking at 21:53 UTC. This event was a small proton flare as well.
Region 10230 continued to develop at a moderate pace. Mixed polarities are currently observed. A minor M class flare is
possible. Flares: C1.3 at 04:41 and C2.9 at 23:55 UTC.
New region 10231 emerged in the southeast quadrant.

Coronal mass ejections (CMEs)

December 17-18: No obviously geoeffective CMEs noted.

December 19: A full halo CME was observed after an M2.7 event in region 10229. The CME was first observed in LASCO C2 images at
22:06 UTC off of the northwest limb and will likely reach Earth sometime between late on December 21 and early afternoon on
December 22 and could cause active to major storm conditions.

Coronal holes

A well placed coronal hole in the southern hemisphere is rotating into view at the southeast limb and will likely reach a
geoeffective position at the central meridian on December 24-25.

Processed SOHO EIT 284 image at 19:06 UTC on December 19. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on December 20-21 due to a coronal stream. Late on December 21 or on
Dec.22 a CME will likely impact Earth and cause active to major geomagnetic storming. Long distance medium wave (AM) band propagation along
east-west paths over high and upper middle latitudes is very poor.

Coronal holes (1)

Coronal mass ejections (2)

M and X class flares (3)

1) Effects from a coronal hole could reach Earth within the
next 5 days.
2) Material from a CME is likely to impact Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48
hours.

Data for all numbered solar regions according to the Solar Region Summary provided by SEC/NOAA. Comments are my own, as is the
STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SEC or where SEC has observed no spots.

Solar region

Date numbered

SEC
spot
count

STAR
spot
count

Location at midnight

Area

Classification

Comment

10218

2002.12.08

1

S18W79

0000

AXX

now spotless

10220

2002.12.09

1

S13W91

0000

AXX

rotated out of view

10223

2002.12.12

4

6

N25W19

0080

CAO

10224

2002.12.12

17

20

S14W21

0050

FRO

beta-gammaclassification was FSO
at midnight

10225

2002.12.13

6

3

N17W18

0040

CAO

classification was HAX
at midnight

10226

2002.12.13

45

37

S28W28

0690

FKC

beta-gamma-delta

10227

2002.12.13

4

3

N07W47

0030

CAO

classification was HSX
at midnight

10228

2002.12.14

2

2

S17W03

0010

BXO

10229

2002.12.14

21

19

N19W03

0230

EAI

beta-gamma

10230

2002.12.17

12

23

S08E32

0210

EAI

beta-gamma
area was 0320 at
midnight

10231

2002.12.19

2

5

S25E13

0020

CSO

Total spot count:

115

118

SSN:

225

208

Monthly solar cycle data

Month

Average solar
flux at Earth

International sunspot number

Smoothed sunspot number

2000.04

184.2

125.5

120.8
cycle 23 sunspot max.

2000.07

202.3

170.1

119.8

2001.11

210.6

106.5

115.5 (+1.5)

2001.12

235.1

132.2

114.6 (-0.9)

2002.01

226.6

114.1

113.5 (-1.1)

2002.02

205.0

107.4

114.7 (+1.2)

2002.03

179.5

98.4

113.4 (-1.3)

2002.04

189.8

120.7

110.5 (-2.9)

2002.05

178.4

120.8

108.8 (-1.7)

2002.06

148.7

88.3

(106.4 predicted, -2.4)

2002.07

173.5

99.9

(102.8 predicted, -3.6)

2002.08

183.6

116.4

(99.6 predicted, -3.2)

2002.09

175.8

109.3

(96.6 predicted, -3.0)

2002.10

167.0

97.5

(93.1 predicted, -3.5)

2002.11

168.7

95.0

(87.8 predicted, -5.3)

2002.12

167.2 (1)

103.9 (2)

(83.5 predicted, -4.3)

1) Running average based on the daily 20:00 UT observed solar flux value at 2800
MHz.
2) Unofficial, accumulated value based on the Boulder (SEC/NOAA) sunspot number. The official
international sunspot number is typically 25-45% less.

This report has been prepared by Jan
Alvestad. It is based partly on my own observations and interpretations, and
partly on data from sources noted in solar
links. Comments and suggestions are always welcome.